This invention relates to an aircraft engine mount and more specifically, although not exclusively, to an arrangement for mounting a gas turbine engine to an aircraft pylon.
A conventional mounting arrangement allows a gas turbine engine to be hung beneath an aircraft wing or else mounted to the fuselage.
It is a consideration in the design of aircraft engine pylons, that the pylon is not only capable of supporting the engine but also withstanding the multidirectional loads experienced by the engine in use and bearing the thrust and reverse thrust produced by the engine. It is an aim to maintain the engine alignment relative to the wing or fuselage so as to avoid off axis loading. However this aim is hampered by thermal expansion of the engine that can occur in use. Thermal expansion is transient and may occur in a localised region or regions of the engine casing rather than in a uniform manner.
Known engine mounts include “two-link” and “three-link” arrangements. An example of a two-link arrangement is shown in US2008/0230675A1. This comprises a mounting block to which two link arms are connected. The link arms generally have the form of triangular members that are each pinned at two apexes to the mounting block. The free apex is pinned to the engine casing. Multiple link attachment points allow the mounting structure to retain torque capability even under failure case scenarios. This arrangement has the disadvantage that, if localised thermal expansion of the engine occurs, the casing may be displaced laterally and downwardly relative to one of the links, causing misalignment with other assemblies such as the nacelle exhaust system.
An example of a three-link arrangement is shown in U.S. Pat. No. 5,078,342A. In this arrangement the link arms are straight and are pinned to the mounting block at one end and to the engine casing at the other. A third straight link arm, for reacting torque loads, is pinned to the casing at its centre-line and to the mounting block at a location spaced from the casing centre-line. The presence of the third link arm may mitigate the lateral/downward displacement caused by localised thermal expansion. However, it can be difficult to accommodate the third link arm, particularly in arrangements in which space between the casing and the mounting block is limited.
The present invention overcomes or substantially mitigates some or all of the above-mentioned and/or other disadvantages of the prior art.